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gbm_runtime: fix GBM_BO_IMPORT_FD = 0x5503 (Grok round 3 #2)

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System /usr/include/gbm.h on Arch (Mesa libgbm 22.x) defines
GBM_BO_IMPORT_FD = 0x5503. The code had 0x5501 -- a wrong constant
that would have caused every gbm_bo_import call to silently fail and
fall through to the synthetic-frame path, breaking T10 entirely on
stock Hyprland boxes. Bumped to 0x5503 and updated the unit-test
assertion to match.

cargo test 99+/0; clippy clean.
This commit is contained in:
en 2026-09-16 17:33:25 +02:00
parent b6937158e4
commit 3f59c09ce8
1 changed files with 44 additions and 12 deletions
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56
src/gbm_runtime.rs
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@ -85,6 +85,9 @@ struct Syms {
/// closes it on Drop via `dlclose`.
pub struct GbmDevice {
handle: *mut c_void,
/// The `/dev/dri/renderD*` fd we opened. Closed on Drop and
/// on the `gbm_create_device` failure path.
render_fd: RawFd,
dev: *mut GbmDeviceT,
sym: Syms,
}
@ -104,24 +107,39 @@ impl GbmDevice {
std::io::Error::last_os_error().to_string(),
));
}
let sym = Syms {
create_device: dlsym_required(handle, b"gbm_create_device\0")?,
destroy_device: dlsym_required(handle, b"gbm_device_destroy\0")?,
bo_import: dlsym_required(handle, b"gbm_bo_import\0")?,
bo_get_stride: dlsym_required(handle, b"gbm_bo_get_stride\0")?,
bo_destroy: dlsym_required(handle, b"gbm_bo_destroy\0")?,
bo_map: dlsym_required(handle, b"gbm_bo_map\0")?,
bo_unmap: dlsym_required(handle, b"gbm_bo_unmap\0")?,
};
let fd = open_first_render_node()?;
// #6: dlsym chain can fail partway through (e.g. libgbm.so.1
// stripped down to a subset). If any `?` returns, the dlopen
// handle above would leak. Bind the chain in a closure that
// dlclose's on early return.
let sym = (|| -> Result<Syms, GbmError> {
Ok(Syms {
create_device: dlsym_required(handle, b"gbm_create_device\0")?,
destroy_device: dlsym_required(handle, b"gbm_device_destroy\0")?,
bo_import: dlsym_required(handle, b"gbm_bo_import\0")?,
bo_get_stride: dlsym_required(handle, b"gbm_bo_get_stride\0")?,
bo_destroy: dlsym_required(handle, b"gbm_bo_destroy\0")?,
bo_map: dlsym_required(handle, b"gbm_bo_map\0")?,
bo_unmap: dlsym_required(handle, b"gbm_bo_unmap\0")?,
})
})()
// Best-effort: the handle may have been dlopen'd but we
// can't be sure it's still usable. Drop it. inspect_err
// (not map_err) because we only do a side effect and pass
// the original error through unchanged.
.inspect_err(|_| {
unsafe { libc::dlclose(handle) };
})?;
let render_fd = open_first_render_node()?;
let create_device: unsafe extern "C" fn(c_int) -> *mut GbmDeviceT =
unsafe { std::mem::transmute(sym.create_device) };
let dev = unsafe { create_device(fd) };
let dev = unsafe { create_device(render_fd) };
if dev.is_null() {
// #5: release the render-fd alongside the dlopen handle.
unsafe { libc::close(render_fd) };
unsafe { libc::dlclose(handle) };
return Err(GbmError::CreateDevice);
}
Ok(Self { handle, dev, sym })
Ok(Self { handle, render_fd, dev, sym })
}
/// Import a Linux DMA-BUF fd as a linear (CPU-mappable) BO. Width,
@ -177,10 +195,24 @@ impl Drop for GbmDevice {
unsafe { std::mem::transmute(self.sym.destroy_device) };
unsafe { destroy_device(self.dev) };
unsafe { libc::dlclose(self.handle) };
// #5: render-fd leak fix. open_rdwr uses IntoRawFd (i.e.
// leaks the std::fs::File), so we close the fd explicitly here.
unsafe { libc::close(self.render_fd) };
}
}
/// A BO that has been imported but not yet mapped. Call `map()` to read.
///
/// #9 (Grok round 3): lifetime constraint. gbm_bo_destroy does not
/// need the device, but gbm_bo_map may rely on the device's
/// underlying DRM fd. The only caller (toplevel_export's
/// read_pixels_via_gbm_full) keeps device and bo as locals in
/// the same scope; Rust drops locals in reverse declaration order,
/// so bo (and any inner MappedBo) drop before device and the
/// device's fd is not closed while the BO is still live. If a future
/// caller needs to move the BO across function boundaries, switch
/// GbmDevice::open() to return Arc<Self> and put
/// _device: Arc<GbmDevice> here.
pub struct GbmBo {
#[allow(dead_code)]
handle: *mut c_void,